JPS5947925A - Overvoltage protecting device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

TECHNICAL FIELD OF THE INVENTION The present invention comprises a discharge section electrically connected in parallel to at least one varistor and each of the varistors, said discharge section being for example an air-corona discharge section [ The present invention relates to an overvoltage protection device which can be formed in a manner such that the discharge point itself is located outside the electrode.

DESCRIPTION OF THE PRIOR ART Such an overvoltage protection device is known from German Patent Application No. 2718188, according to which, in the event of a relatively low overvoltage and a correspondingly low leakage discharge current, A Advantageously, the IJ star acts as a first protection device. In such a case) the voltage drop occurring across the Lister is sufficiently large to cause a spark discharge section, such as the air-corona discharge section described in this example, to flash over; Only when the load is relatively large is the discharge section also used as a protective device and thus /S l
) acts as an overvoltage protection device for the star. In such a device, the discharge section limits the voltage at the load and keeps the voltage at risk approximately constant. However, it is also possible to provide a discharge section different from the air-corona discharge section, for example a gas discharge arrester, if the desired current load characteristics are achieved. In most cases, such an overvoltage protection device can be provided, in which case it is advantageous to use it in areas where direct lightning strikes are expected. For example, such overvoltage protection devices are installed in electrical equipment directly in buildings where lightning strikes are expected.

However, in this case, the current-voltage characteristics of the Nonoristor change due to the long-lasting falling current of the lightning current (so-called 2-volt trailing current) due to frequent loads, that is, changes in the current-voltage characteristics over time. It is unavoidable that resistors will lead to unacceptable leakage currents at normal operating voltages.Not only will such currents be charged, but they will also cause an unacceptable increase in the ground potential and possibly even damage to the nonoristor and therefore the equipment. The varistor may be heated to an unacceptably high level.In some cases, the varistor may be destroyed.Also, for example, if the characteristic curve of such a varistor changes, the surge current to be leaked may become too large. Even if the current flows to the Lister, a sufficiently large voltage drop will not occur in the Nono Listor, and there is a risk that the discharge section will not reach the required ignition voltage and will no longer function as a lightning arrester.

From German Utility Model No. 7501349 and German Patent Application No. 8105608, a valve arrester is known which has a series connection consisting of a discharge section, a variable resistance, and a fuse piece. If heated to an unacceptable level, the fuse piece (solder joint) will melt. As a result, the entire valve arrester is disconnected from the network, ie it is no longer activated as a whole.

OBJECTS OF THE INVENTION In contrast to the above-mentioned prior art, the object of the present invention is to provide an overvoltage protection device of the type mentioned at the outset, with the risk of damage to the nonoristor due to frequent loads such as surge currents, e.g. lightning currents. - changes in the voltage characteristic curve) and thus large leakage currents, the operation of the discharge section is not impaired and the functionality of the overvoltage protection device is maintained as a whole.

According to the invention, this problem is achieved in an overvoltage protection device of the type mentioned at the outset by the features and features of claims 1 and 5.

This ensures that unacceptably large leakage currents do not flow continuously, and in particular that no sufficient ignition voltage occurs in the discharge section. In contrast to the devices described in the aforementioned German Utility Model Registration Nos. 7501349 and 8105608, the device of the present invention is not a complete overvoltage protection device, but a branch of a parallel circuit with a nonoristor. This is advantageous because it only shuts off and therefore prevents it from operating.

The discharge path therefore protects the downstream connected devices as before. The discharge section itself has a current capacity that is sufficient to reliably leak and interrupt, for example, lightning tail currents having the frequency of the mains. This means that the device becomes independent of any line fuses that may be provided during each operating period.

This is achieved, for example, by providing a discharge section with two electrodes with an insulating layer in between, the insulating layer being able to push the arc out when heated by the flashing arc or to blow it out and cool it. If it is made of a material that emits a gas that extinguishes the arc, the subsequent supply current is interrupted (cf. DE 29 34 238). Particularly in low-voltage installations, it is recommended to provide the above-mentioned discharge section. In addition, for example, the above-mentioned insulating material (POM) that generates hydrogen gas.

Although mica can be used as an insulating material instead of Teflon (trade name, etc.), mica does not have this effect.

In an embodiment of the invention, the branch with the varistor is provided with an electrically triggered monitoring and disconnection device.

Further, in the embodiment of the present invention, an indicating device is provided, so that when a parallel branch having a varistor is cut off by the monitoring-cutting device, the indicating device is connected, so that it is possible to detect that the no-no-ristor has been cut off. The operator can be notified.

Description of examples The invention will now be explained with reference to illustrated embodiments.

The basic circuit diagram in Figure 1 shows the voltage supply line or 1
and earth or equipotential line 2, on the one hand a discharge section, for example an air-corona discharge section (Luft-Gleit-
Uberschlags-Funkenstrecke
) 3 and A +) star 4 and solder point 5 on the other hand
It has a parallel connection with a series connection of monitoring and disconnection devices in the form of . An indicating device 6 with a monitoring or test key 7 is also provided parallel to this parallel connection.

FIG. 2 shows a corresponding three-phase embodiment, connecting voltage supply phase lines Ll, L2 and L3 (or 1) of the distribution network, earth line 2 or equipotential line PAS and neutral line N (or 8). have The casing of the overvoltage protection device is indicated by a dashed line 9.

The line l○ between the equipotential line PAS and the earth line 2 on the one hand and the neutral line 8 on the other hand has only a discharge section 3 and no parallel branches with the nonolister 4 and the monitoring and disconnection device 5. . Further, a fuse 11 can be provided.

However, this fuse is patented in Federal Republic of Germany Patent No. 2934.
This is not necessary when the discharge section described in the specification of No. 238 is provided.

For example, when using the discharge section described in German Patent No. 2718188, the following electrical data are obtained. However, the present invention is not limited thereby.

Power supply voltage: 220/380V fuse 11
: Parallel branch of e.g. 50A NonoRister and monitoring device: configured for a 5kA impulse current with a rise time of 8μs and a fall time of 20μs to a value of 50, corresponding to approximately 0.1As and 500J7Ω .

Airborne corona discharge section: For impulse current of 1QQKA It consists of approximately 1 QAs and and 500 min/Ω.

Figure 3 shows the current (I)-voltage (U)-characteristic curves of risks 1, in which case 12 shows the characteristic curves under normal conditions, and 13 and 14 show the characteristic curves already present at relatively small voltages. 1 shows the characteristic curve of a faulty nonoristor in which an unacceptably large current flows; In such a case, the monitoring device 5 shuts off the damaged IJ star 4. This is done thermally using a solder that melts when the varistor is heated accordingly (see for example FIGS. 4 et seq.). This can also be done using an electrically actuated fuse or breaker (for which C is not shown), in which case the breaker can be adjusted to interrupt the leakage current of the nonoristor in the range of mA.

, 6 risks, the protective effect of the device is maintained by the discharge section. - An indicating device (optical or acoustic) can be provided to monitor that the ζ ring has been interrupted, this indicating device being indicated at 6 in the embodiment of FIG. , it indicates that the A IJ stall has been shut off by the shut off device 5 provided in the parallel branch with the component head, 5. The operation of this indicating device can be monitored by means of the test key 7. Of course, the three-phase circuit of FIG. 2 can also be provided with the monitoring and indicating device described above, but this is not shown in FIG. 2 for reasons of simplicity. However, such a device is the fourth
Shown below.

The embodiments shown in FIGS. 4 to 7 are based on the casing or basic
5 is made of an insulating material and has three connecting conductor paths 1', the conductor paths 1' being connected to the connecting lines Ll, L2 . A yoke-shaped connection terminal 16' for L3 (also 1) is connected to a tightening screw 16 for connection to spark gaps 17-19. A fourth conductor path 8' is also provided between the connecting terminal 16' for the yoke-shaped neutral conductor 8 and the connecting terminal 2o for the equipotential earth conductor as well as the clamping screw 16 - so that during operation is conductor path 8
No voltage is applied to .

In a preferred embodiment of the invention, the conductor tracks 1' and 8' are each linear and have a cross-sectional area corresponding to a conductor capable of withstanding lightning currents, so as to be able to carry the required current. Stable tightening screws and connection terminals 16,
16'. The conductor path, connecting terminal, and tightening screw have a required current of, for example, 500 KJ/Ω.
In the lower part of the clamping screw 16, a spark gap for carrying a flashing current, which advantageously has an electrode 17, an insulating member 18 and a common earth plate 19, is configured to withstand the electrodynamic demands of a lightning current. is provided. In that case, the insulating member 18
has a peripheral ring boxwood 18' insulating each electrode 17 from the ground plate 19. The electric arc of the corona discharge formed in that case is indicated by 18" (see Fig. 7). Since the tightening screw 16 passes through the insulating member 18 and is screwed into the basic frame 15 made of insulating material, one tightening screw No flashover discharge occurs between 16 and ground plate 19.

The equipotential line or ground line 2 is connected to a terminal 20 which is also formed in a U-shaped curve. A IJ star 4 and a monitor are connected between the conductor path 1' and the ground plate 19, respectively.
A parallel branch with disconnecting devices 5, 6 and 7 is connected, the component 42.5 being arranged spatially close to the conductor path 1'. Nono Rinta beef is placed side by side so as not to take up too much space. In that case, 5 designates a solder point for electrically connecting the contact 25 with the conductor part 22 with the spring 22 connected thereto. Spring 2
2 is connected to the corresponding conductor path 1' at 23, and 2
4 indicates an additional mechanical attachment point which is insulated from the conductor track 1'. Paths 23, 22, 5.21.25 reaching 19
If an unacceptably large leakage current occurs in and Φ,
The solder point 5 melts and the spring 22 moves in the direction of the arrow 22' due to the inherent stress until it comes into contact with the contact 26. The melting temperature of the aforementioned solder is, for example, 150°C. Contact 26 is also shown in the basic circuit diagram of FIG. This indicates that the ring 4 has been separated via the ring 5. The key device 7 is shown in FIGS. 5 and 6. Bin 7' of the key device is the aforementioned monitoring device;
The power supply voltage applied to the component 21 via the spring 22 and the connection terminal 23 is detected. The supply voltage is then applied to the contact 25 in the unreleased position of FIG. When the solder connection 5 is opened, it is then interrupted by the spring 22.

The apparatus shown in FIGS. 4 to 7 can be constructed without using much space. In this case, a disk-shaped hole ζ and a ring Φ can be provided in parallel to the conductor track 1'. In that case, the upper 2
Nonolinters corresponding to the two conductors L 1 and L 2 can be provided adjacent to each other and connected to the earth plate 19 via a common earth contact 4'.

[Brief explanation of the drawing]

Fig. 1 is a schematic circuit diagram showing the device of the present invention for a single-phase circuit, Fig. 2 is a schematic circuit diagram showing the device of the present invention for a three-phase circuit, and Fig. 3 shows the current-voltage characteristic curve of the risk. 4 is a plan view showing a three-phase embodiment of the overvoltage protection device according to the present invention, FIG. 5 is a sectional view taken along the v-v line in FIG. 4, and FIG. FIG. 7 is an enlarged sectional view showing the main part of FIG. 5 in detail. 3゛°°discharge, 4...very risk, 5...solder points,
6... Indication device, 7... Test key, 1],... Fuse, 15... Casing or basic rack, 16...
・Tightening screw, 16', 20, 23...Connection terminal, 1
7... Electrode, 18... Insulating member, 18'... Ring boxwood, 19... Earth plate, 22... Spring, 25...
...Risk contact body, 26... Contact sub-representative patent attorney Toshio Yano 4 7 7' 6 Continued from page 1 @ Applicant Hans Joachim Sohn Federal Republic of Germany Nuremberg Steilerstrasse 21

Claims (1)

[Scope of Claims] 1. In an overvoltage protection device having at least one nono-ristor and a discharge section electrically connected in parallel to the no-no-lister, the Overvoltage protection device, characterized in that a monitoring device (5) is provided which maintains the current-voltage characteristic curve (12) of the nono-ristor and shuts off said nono-ristor in the event of a corresponding fault. 2. Overvoltage protection device according to claim 1, in which the monitoring device (5) is configured as a thermally controllable device that is heated and shut off accordingly by the leakage current of risk (4). . 3. Overvoltage protection device according to claim 2, characterized in that the monitoring device (5) is constructed as a solder connection which is switched off in the event of a corresponding thermal load. 4. The overcurrent protection device according to claim 1, wherein the monitoring device comprises a fuse or a breaker capable of setting and adjusting the leakage current of the Nonoristor to a predetermined value and activated by the leakage current. 5. In an overvoltage protection device having at least one varistor and a discharge section electrically connected in parallel to the varistor, the current-voltage characteristic curve of the varistor is connected to the branch of the parallel circuit with the varistor (4); (12) and, in the event of a corresponding failure, a monitoring device (5) is provided which interrupts the above-mentioned risks, and in which the heat load and the a conductor track (1', 8') through which a current flows depending on the dynamic load, said conductor track being configured as a parallel branch with a discharge section (3) or as part of this parallel branch; A discharge section (3; or 17.18
．． 19) and is provided spatially close to a conductor path corresponding to the associated nonoristor (4).